Preventing rapid collision with stock during linking moves.

[Anonymous]

I'm getting all kinda of collisions from linking moves on my adaptive clearing operation.  I am also getting collisions with the tool holder even though the tool holder is obviously not colliding with anything.   I really need some help finishing this project for a job.

I have my lead in and out set to 0 but fusion reports lots of the retracts as collisions and adds a little movement anyway that causes a collision.  

[johnswetz1982 · Accepted solution]

Wow you got a lot going on with this. The short answer is to increase not decrease the leadins/outs and vertical leadins. That should start solving some of your problems. A lot of the other stuff you are making way more complicated than it needs to be. I would look into patterns in CAM, not machining past your centerline/axis if your going all around the part and moving the original up so that you dont have a lot of stock at the top.

What kind of machine/control is this done on?

[Anonymous]

This is a manually indexed 3d milling template for milling stls that 4 sided machining leaves too much on.  I went past the center line because I wanted to machine the back of some of those faces that are obscured when machining from other angles.   The geometry of the model I am trying to machine is difficult because it has three arms around a center post.   machining  the inside part of those arms is proving to be a challenge.   I am machining this on a MillRight Power Route (prosumer level benchtop cnc)

[Anonymous · Accepted solution]

How would I use cam component patterns to do multi-sided machining?  If I don't have to clone toolpaths for each side that would be pretty sweet!  I also dont understand the lead in/out stuff then.  I turned it all the way down because sometimes the lead moves themselves cause collisions.  What should my lead in/out be set to for a .5 in tool for example.  Should it be set to some multiple of the tool diameter?

[johnswetz1982 · Accepted solution]

-You can at least use mirror for the 2 symmetrical sides.

-Since you are only using straight bits going past centerline/axis makes no sense to me (other than going lower than your stock to leave, I found that out the tough way).

-It may make sense to have your work offset be at the center of rotation.

-For link moves, generally You would want at least the tool radius for the moves (use Dia if still getting errors)because the control will position at uncompensated rapid, then do a compensation move when it starts the feed cutting feed rate. With 0 for a value the compensation move is still "rapid" before switching to feed resulting in a "collision". It may not matter if in would but would most likely snap the bit from shock if in metal. It will add to machining time because the lead moves are generally set slower but its better to be slower not snaps tools and to be quick and have a bunch of broken tools.    

[Anonymous]

Will that work if the model isn't symmetrical though?  Mine isnt.

Also how would I set my zero on my machine if the work offset is the center of the stock?  What do I use as a datum?  I'm completely new to multisided milling in case you havent guessed yet.

[johnswetz1982 · Accepted solution]

Sorry, I was only looking at the one side. I did not see the difference in the "hand guard" side.

Since you are leaving stock on the top and bottom (vertically) you would figure out what the halfway of your stock thickness is and use that for your center height. I would just do it different but I am use to a metal lathe or 5 axis mill for this kind of work. With the way i am use to the stock is auto indexed so you do not need more than one setup. That is why I was asking what kind of control and machine it was.

If you think you can do it this way by all means just fix the linking moves issue and get it done. 

[Anonymous]

You have been a great help!  All of my collisions are resolved now.  I'm playing with your suggestion of limiting the machining to halfway.  Thanks so much!  I'll post a link to a video of me cutting it later!

It's just a regular cnc router running on grbl.

[johnswetz1982]

Do halfway - stock to leave (meaning deeper), else you will have a thin web of material on your center axis/plane. so if stock to leave is 1.5mm your bottom height tab should be [Selection]>File origin and -1.5 additional offset.

[Anonymous]

Thanks, but my parallel path takes care of the remainder. (I'm setting it to machine just past the centerline.)

I'm actually doing two rough ops and a finishing op before I flip the part.  The finishing pass leaves no stock.